Impeller and rotary machine

ABSTRACT

This impeller is equipped with: an impeller body for rotating around an axis along with a rotating shaft, formed from a resin and shaped as a disk; compressor blades provided on a hub surface of the impeller body; and a reinforcing ring which is formed from a resin and reinforcing fibers in a ring shape extending in the circumferential direction, and engages, from the outer peripheral side, a step section formed in the back surface of the impeller body and having a fitting surface facing the outer peripheral side.

TECHNICAL FIELD

The invention relates to an impeller provided in a rotary machine, and a rotary machine including an impeller.

Priority is claimed on Japanese Patent Application No. 2014-245157, filed Dec. 3, 2014, the content of which is incorporated herein by reference.

BACKGROUND ART

While the global efforts of earth environment preservation proceed, intensification of regulations regarding exhaust gas or fuel efficiency in internal combustion engines, such as engines of automobiles is under way. Turbochargers are rotary machines that can enhance effects of fuel efficiency improvement and CO₂ reduction by sending compressed air into an engine to combust fuel compared to natural intake engines.

In the turbochargers, a turbine is rotationally driven with exhaust gas of an engine, thereby rotating an impeller of a centrifugal compressor. The air compressed by the rotation of the impeller is raised in pressure by being reduced in speed by a diffuser, and is supplied to the engine through a scroll flow passage. In addition, as methods for driving the turbochargers, not only methods of being driven with exhaust gas but also, for example, methods using electric motors, methods using prime movers, and the like are known.

As an impeller of a turbocharger, an impeller using a complex material (hereinafter referred to as a resin) of synthetic resins, such as carbon fiber reinforced plastic, is known as described in, for example, PTL 1. Here, such a resin impeller has low rigidity compared to a metallic impeller, and if the resin impeller rotates, the amount of deformation thereof becomes large under the influence of a centrifugal force. For this reason, a boss hole into which a rotating shaft is fitted may be increased in diameter, and rotation balance may be impaired.

In view of such a problem, in the impeller described in PTL 1, the deformation of the impeller by the centrifugal force is suppressed by providing a back surface part with a metallic ring.

CITATION LIST Patent Literature

[PTL 1] Japanese Unexamined Utility Model Registration Application Publication No. 3-10040

SUMMARY OF INVENTION Technical Problem

As disclosed in PTL 1, since the impeller is formed of the resin in a case where the metallic ring is used, the materials of the impeller and the ring are different from each other. Therefore, the metallic ring has a larger coefficient of linear expansion than the impeller made of the resin. As a result, there are possibilities that, depending on operation conditions, a stress generated in the impeller cannot be distributed to the ring and the deformation of the impeller cannot be suppressed. Additionally, since the density of the metal is high compared to the resin, the diameter of the ring itself may be increased due to the influence of a centrifugal force, deformation of the impeller cannot be suppressed, and it is difficult to guarantee the reliability of the impeller.

The invention provides an impeller and a rotary machine that can guarantee reliability even if resin materials are used.

Solution to Problem

According to a first aspect of the invention, an impeller includes an impeller body that is formed of a resin, forms a disk-like shape, and rotates about a rotation center axis together with a rotating shaft; a plurality of blades provided on a front surface side of the impeller body; and a reinforcing ring that is formed on a back surface of the impeller body, is fitted to a step section, having a surface facing an outer peripheral side, from the outer peripheral side, is formed of a resin and reinforcing fibers, and forms an annular shape in a circumferential direction of the impeller body.

According to such an impeller, since the reinforcing ring is formed of the resin and the reinforcing fibers, the material of the impeller body and the material of the reinforcing ring become substantially the same. For this reason, a difference between the coefficients of linear expansion of the impeller body and the reinforcing ring becomes small. As a result, the constraint force of the impeller body can be inhibited from decreasing due to an increase in the diameter of the reinforcing ring caused by thermal expansion. Moreover, since the density of the resin is low, the constraint force of the impeller body can be inhibited from decreasing by the diameter of the reinforcing ring being increased due to a centrifugal force. Additionally, since the reinforcing ring includes reinforcing fibers, rigidity can be improved, the constraint force of the impeller body can be inhibited from decreasing due to a diameter increase caused by the centrifugal force of the reinforcing ring itself. Therefore, a centrifugal force that acts on the impeller body can be distributed to the reinforcing ring, the stress of the impeller body caused by the centrifugal force can be reduced, and it is possible to suppress deformation of the entire impeller.

According to a second aspect of the invention, the step section in the above first aspect may be formed at a position of ⅔ of a diameter dimension between the rotation center axis and an outer peripheral end of the impeller body from the rotation center axis.

Since the step section is formed at such a position, the reinforcing ring is provided at the position of ⅔ of the radial dimension of the impeller body from the central axis of the impeller body. By providing the reinforcing ring at such a position, the stress of the impeller body caused by a centrifugal force can be reduced more effectively, and deformation of the entire impeller can be suppressed.

According to a third aspect of the invention, the step section in the above first aspect may be formed such that the center of the reinforcing ring in a radial direction is located at a position that is larger than 0.1 times a diameter dimension between the rotation center axis and an outer peripheral end of the impeller body from the rotation center axis and is smaller than the diameter dimension.

Since the step section is formed at such a position, the stress of the impeller body caused by a centrifugal force can be reduced more effectively, and deformation of the entire impeller can be suppressed.

According to a fourth aspect of the invention, the impeller body in the above first aspect may be provided with a boss part that protrudes from the back surface and has the rotating shaft fitted thereto, and the step section may be formed at the boss part.

According to the above aspect, the reinforcing ring is provided at the boss part provided in the impeller body. Accordingly, a stress caused by a centrifugal force at the boss part can be reduced, and deformation of the entire impeller can be suppressed.

According to a fifth aspect of the invention, a width dimension of the reinforcing ring in a radial direction and a blade thickness dimension of the blades in the circumferential direction in the first to fourth aspects may be the same, and a thickness dimension of the reinforcing ring in a direction of the rotation center axis may be larger than the width dimension of the reinforcing ring in the radial direction.

Since the reinforcing ring is formed with such a dimension, the stress of the impeller body caused by a centrifugal force can be reduced more effectively, and deformation of the entire impeller can be suppressed.

According to a sixth aspect of the invention, the reinforcing ring in the first to fifth aspects may be disposed such that the reinforcing fibers extend in the circumferential direction of the impeller body.

If a centrifugal force acts on the reinforcing ring, a tensile force acts in the circumferential direction. For this reason, since the reinforcing fibers extends in the circumferential direction that is a direction in which this tensile force acts, deformation of the reinforcing ring by such a tensile force itself can be suppressed. Therefore, the constraint force of the impeller body can be inhibited from decreasing, and a centrifugal force that acts on the impeller body can be distributed to the reinforcing ring. Therefore, the stress of the impeller body can be reduced, and deformation of the entire impeller can be suppressed.

According to a seventh aspect of the invention, an impeller includes an impeller body that is formed of a resin, forms a disk-like shape, and rotates about a rotation center axis together with a rotating shaft; a plurality of blades provided on a front surface side of the impeller body; and a reinforcing ring that is formed on a back surface of the impeller body, is provided at a step section, having a surface facing an outer peripheral side, from the outer peripheral side, is formed of only reinforcing fibers, and forms an annular shape in a circumferential direction of the impeller body.

According to such an impeller, since the reinforcing ring is formed of only the reinforcing fibers, a difference between the coefficients of linear expansion of the impeller body and the reinforcing ring becomes small. As a result, the constraint force of the impeller body can be inhibited from decreasing due to an increase in the diameter of the reinforcing ring caused by thermal expansion. Additionally, since the density of the carbon fibers is low, the constraint force of the impeller body can be inhibited from decreasing by the diameter of the reinforcing ring being increased due to a centrifugal force. Therefore, a centrifugal force that acts on the impeller body can be distributed to the reinforcing ring, the stress of the impeller body caused by the centrifugal force can be reduced, and deformation of the entire impeller can be suppressed.

According to an eighth aspect of the invention, the impeller may further include a second reinforcing ring that is disposed in the circumferential direction of the impeller body inside the impeller body in the first to seventh aspects and forms an annular shape.

By disposing the second reinforcing ring inside the impeller body made of the resin in this way, the rigidity of the impeller body can be further improved. Additionally, since the second reinforcing ring is disposed inside the impeller body, slip-out from the impeller body can be suppressed even if a material having a different coefficient of linear expansion from the impeller body is used. Therefore, a centrifugal force that acts on the impeller body can be distributed to the second reinforcing ring, a stress generated in the impeller body due to the centrifugal force can be further reduced, and deformation of the entire impeller can be suppressed.

According to a ninth aspect of the invention, a rotary machine includes the impeller in the above first to eighth aspects; and a rotating shaft that is attached to the impeller and rotates together with the impeller.

According to such a rotary machine, since the above reinforcing ring is provided, the constraint force of the impeller body can be inhibited from decreasing. Therefore, a centrifugal force that acts on the impeller body can be distributed to the reinforcing ring, and a stress generated in the impeller body due to the centrifugal force can be reduced.

Advantageous Effects of Invention

According to the above-described impeller and rotary machine, the reinforcing ring is provided. Thus, even if resin materials are used, it is possible to guarantee reliability.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal sectional view illustrating a turbocharger related to a first embodiment of the invention.

FIG. 2 is a longitudinal sectional view illustrating an impeller of the turbocharger related to the first embodiment of the invention.

FIG. 3 is a graph of analysis results illustrating effects of a reinforcing ring in the impeller of the turbocharger of the first embodiment of the invention, a horizontal axis represents coordinates in a direction of an axis, and a vertical axis represents ratios of stresses generated in an impeller body. Additionally, a dashed line represents cases where no reinforcing ring is provided, and a solid line represents the impeller of the first embodiment.

FIG. 4 is a longitudinal sectional view illustrating an impeller of a turbocharger related to a second embodiment of the invention.

FIG. 5 is a graph of analysis results illustrating effects of a reinforcing ring in the impeller of the turbocharger of the second embodiment of the invention, a horizontal axis represents coordinates in the direction of the axis, and a vertical axis represents ratios of stresses generated in the impeller body. Additionally, a dashed line represents cases where no reinforcing ring is provided, a solid line represents the impeller of the first embodiment, and a two-dot chain line represents the impeller of the second embodiment.

FIG. 6 is a longitudinal sectional view illustrating an impeller of a turbocharger related to a third embodiment of the invention.

FIG. 7 is a longitudinal sectional view illustrating an impeller of a turbocharger related to a modification example of the third embodiment of the invention.

DESCRIPTION OF EMBODIMENTS First Embodiment

Hereinafter, a turbocharger 1 (rotary machine) related to an embodiment of the invention will be described.

As illustrated in FIG. 1, the turbocharger 1 includes a rotating shaft 2, a turbine 3 and a compressor 4 that rotate together with the rotating shaft 2, and a housing coupling part 5 that couples the turbine 3 and the compressor 4 and supports the rotating shaft 2.

In the turbocharger 1, a turbine 3 is rotated with exhaust gas G from an engine (not illustrated), and air AR compressed by the compressor 4 is supplied to the engine with the rotation.

The rotating shaft 2 extends in a direction of an axis O. The rotating shaft 2 rotates about the axis O.

The turbine 3 is disposed on one side (the right side of FIG. 1) in the direction of the axis O.

The turbine 3 includes a turbine impeller 14 that has the rotating shaft 2 attached thereto and has a turbine blade 15, and a turbine housing 11 that covers the turbine impeller 14 from an outer peripheral side.

The rotating shaft 2 is fitted into the turbine impeller 14. The turbine impeller 14 is rotatable around the axis O together with the rotating shaft 2.

The turbine housing 11 covers the turbine impeller 14. A scroll passage 12, which extending from a leading edge part (an end part on a radial outer side) of the turbine blade 15 toward the radial outer side, is formed in an annular shape about the axis O at a position on the radial outer side, and allows the inside and outside of the turbine housing 11 to communicate with each other therethrough, is formed in the turbine housing 11. The turbine impeller 14 and the rotating shaft 2 are rotated by the exhaust gas G being introduced into the turbine impeller 14 from the scroll passage 12.

A discharge port 13 opening to one side of the axis O is formed in the turbine housing 11. The exhaust gas G that has passed through the turbine blade 15 flows toward one side of the axis O, and is discharged from the discharge port 13 to the outside of the turbine housing 11.

The compressor 4 is disposed on the other side (the left side of FIG. 1) in the direction of the axis O.

The compressor 4 includes a compressor impeller 24 that has the rotating shaft 2 attached thereto and has a compressor blade 25, and a compressor housing 21 that covers the compressor impeller 24 from the outer peripheral side.

The rotating shaft 2 is fitted into the compressor impeller 24. The compressor impeller 24 is rotatable around the axis O together with the rotating shaft 2.

The compressor housing 21 covers the compressor impeller 24. A suction port 23 opening to the other side of the axis O is formed in the compressor housing 21. The air AR is introduced from the outside of the compressor housing 21 through the suction port 23 into the compressor impeller 24. Then, by a rotative force from the turbine impeller 14 being transmitted to the compressor impeller 24 via the rotating shaft 2, the compressor impeller 24 rotates around the axis O and the air AR is compressed.

A compressor passage 22, which extend from a trailing edge part (a downstream end part of a flow of the air AR) of the compressor blade 25 toward the radial outer side, forms an annular shape about the axis O at a position on the radial outer side, and allows the inside and outside of the compressor housing 21 to communicate with each other therethrough, is formed in the compressor housing 21. The air AR compressed by the compressor impeller 24 is introduced to the compressor passage 22, and is discharged to the outside of the compressor housing 21.

The housing coupling part 5 is disposed between the compressor housing 21 and the turbine housing 11 to couple these housings. The housing coupling part 5 covers the rotating shaft 2 from the outer peripheral side. The housing coupling part 5 is provided with a bearing 6. The rotating shaft 2 is supported by the bearing 6 so as to become rotatable relative to the housing coupling part 5.

Next, the compressor impeller 24 will be described in detail with reference to FIG. 2.

The compressor impeller 24 includes a plurality of the compressor blades 25, an impeller body 31 that supports the compressor blades 25 on a hub surface 31 aformed on a front surface side, and a reinforcing ring 41 fitted to a back surface 32 of the impeller body 31.

The plurality of compressor blades 25 are provided apart from each other in a circumferential direction of the rotating shaft 2 and the impeller body 31. A flow passage FC through which the air AR flows is formed between the compressor blades 25 that are adjacent to each other in the circumferential direction. The compressor blades 25 are formed of a resin in the present embodiment.

Here, as resins used for the compressor blades 25, for example, polyether sulfone (PES), polyether imide (PET), polyether ether ketone (PEEK), polyether ketone (PEK), polyether ketone ketone (PEKK), poly ketone sulfide (PKS), polyaryl ether ketone (PAEK), aromatic polyamide (PA), polyamide imide (PAI), polyimide (PI), and the like are exemplified.

In addition, the compressor blades 25 are not limited to the case where the compressor blades are a resin, and may be made of a metal or the like.

The impeller body 31 forms a disk-like shape and supports the compressor blades 25 on the front surface side, that is, the compressor blades 25 on the other side in the direction of the axis O so as to protrude from the hub surface 31 a.

The impeller body 31 is made of the same resin as that of the above-described compressor blades 25. A step section 36 having a fitting surface 37 that faces the outer peripheral side (radial outer side) is formed on the back surface 32 of the impeller body 31, that is, a surface on one side in the direction of the axis O.

A boss hole section 31 b having the rotating shaft 2 inserted therethrough and fitted thereinto is formed in a region on a radial inner side in the impeller body 31.

More specifically, the step section 36 is formed so as to be recessed annularly about the axis O from the back surface 32 of the impeller body 31 toward the other side in the direction of the axis O, and splits the back surface 32 into a first back surface 32A located on the radial outer side and a second back surface 32B located on the radial inner side.

The first back surface 32A and the second back surface 32B are formed in a radial direction. The fitting surface 37 is disposed between the first back surface 32A and the second back surface 32B, and the step section 36 is formed on the back surface 32 by connecting the first back surface 32A and the second back surface 32B.

In addition, the second back surface 32B is inclined so as to face one side in the direction of the axis O while being curved in a concave shape to the other side in the direction of the axis O as it becomes closer to the radial inner side, and is continuous with the boss hole section 31 b after being bent so as to run in the radial direction from a halfway position.

In the present embodiment, the fitting surface 37 in this step section 36 is formed at a position of ⅔ of a diameter dimension R between the axis O and an outer peripheral end (an end part on the outermost side in the radial direction) of the impeller body 31 from the axis O that becomes a rotation center axis of the impeller body 31.

The reinforcing ring 41 forms an annular shape, and is fitted to the step section 36 of the impeller body 31 from the outer peripheral side. That is, fitting to the step section 36 is made as an inner peripheral surface thereof contacts the fitting surface 37 in the step section 36. The reinforcing ring 41 is formed in a shape and a size such that, in a state where the reinforcing ring 41 is fitted, the center of the reinforcing ring 41 coincides with the axis O and the reinforcing ring 41 is smoothly continuous with the second back surface 32B of the impeller body 31.

In the present embodiment, the shape of a cross-section including the axis O forms a rectangular shape, the thickness dimension in the direction of the axis O coincides with the length dimension of the fitting surface 37, and the width dimension in the radial direction is larger than the thickness dimension in the direction of the axis O.

The reinforcing ring 41 is formed of the same resin as that of the compressor blades 25 and the impeller body 31 and further reinforcing fibers. That is, the reinforcing ring 41 is formed of a complex material (carbon fiber reinforced plastic) consisting of resin and carbon fibers, in the present embodiment. Here, the reinforcing fibers in the reinforcing ring 41 are not limited to the carbon fibers, and may be glass fibers, Whisker, and the like.

The reinforcing ring 41 may be provided so as to be fitted into the impeller body 31 by insert molding, or may be provided by recoating the fitting surface 37 in the step section 36 with a fiber reinforcing resin.

According to the turbocharger 1 of the present embodiment described above, since the reinforcing ring 41 of the compressor impeller 24 is formed of the complex material including the resin, the material of the reinforcing ring 41 and the material of the impeller body become substantially the same. For this reason, a difference between the coefficients of linear expansion of the impeller body 31 and the reinforcing ring 41 becomes small. As a result, the constraint force of the impeller body 31 can be inhibited from decreasing due to an increase in the diameter of the reinforcing ring 41 caused by thermal expansion.

Moreover, the density of the resin is low compared to the metal or the like. For this reason, the constraint force of the impeller body 31 can be inhibited from decreasing by the diameter of the reinforcing ring 41 being increased due to a centrifugal force.

Additionally, since the reinforcing ring 41 includes the carbon fibers as the reinforcing resin, the rigidity thereof can be improved. For this reason, the constraint force of the impeller body 31 can be inhibited from decreasing due to a diameter increase caused by the centrifugal force of the reinforcing ring 41 itself.

As a result, a centrifugal force that acts on the impeller body 31 can be distributed to the reinforcing ring 41, and a stress generated in the impeller body 31 due to the centrifugal force can be reduced. For this reason, by virtue of the reinforcing ring 41 formed of the complex material including the resin and the reinforcing fibers, deformation can be sufficiently suppressed even if the resin is used for the impeller body 31.

Moreover, the step section 36 of the impeller body is formed at the position of ⅔ of the diameter dimension R between the axis O and the outer peripheral end of the impeller body 31 from the axis O that becomes the rotation center axis of the impeller body 31. For this reason, the reinforcing ring 41 is provided at the position of ⅔ of the diameter dimension R of the impeller body 31 from the rotation center axis of the impeller body 31.

Analysis results obtained by plotting the ratios of stresses generated in the impeller body 31 in a case where the center of the reinforcing ring 41 in the radial direction is provided so as to be located at a position of 0.6 (about ⅔) times the diameter dimension of the impeller body 31 for individual relative position coordinates of the impeller body 31 in the direction of the axis O are illustrated in FIG. 3. The ratios of the stresses are ratios in a case where a maximum value of a stress generated in the impeller body 31 in the present embodiment is set to about 0.7.

In this analysis, as a position coordinate in the direction of the axis O in the compressor impeller 24, an end part position on the other side of the axis O that becomes a side into which the air AR flows is set as 0, and an end part position on one side of the axis O that becomes a side from which the air AR flows is set as 1.0. Additionally, the formation range of the compressor blades 25 is about 0.3 to 0.8.

Moreover, as analysis conditions, a thickness dimension b of the reinforcing ring 41 in the direction of the axis O is 0.03 times the thickness of the impeller body 31 in the direction of the axis O and a width dimension a of the reinforcing ring 41 in the radial direction is 0.03 times the external diameter dimension of the impeller body 31.

According to the analysis results of FIG. 3, since the reinforcing ring 41 is provided at the position of about ⅔ of the diameter dimension R of the impeller body 31, it can be confirmed that a stress can be markedly reduced at a position where a relative position coordinate in the direction of the axis O becomes larger than about 0.6 compared to a case (dashed line) where the reinforcing ring 41 is not provided.

Stresses decrease gradually at position coordinates of about 0.95 to about 0.6, and a stress ratio is suppressed to about 0.55 at a position of 0.95. On the other hand, in a case where the reinforcing ring 41 is not provided, stresses becomes gradually large as position coordinates become large, and a stress ratio 0.8 is exceeded at a position of about 0.85.

Therefore, by providing the reinforcing ring 41 at the position of about ⅔ of the dimension of the radial direction of the impeller body 31, a stress generated in the impeller body 31 can be more effectively reduced, and deformation of the entire compressor impeller 24 can be suppressed.

In addition, in the present embodiment, the fitting surface 37 in this step section 36 is not limited to a case where the fitting surface is formed at the position of ⅔ of the diameter dimension R of the impeller body 31 from the rotation center axis (axis O) of the impeller body 31. The fitting surface has only to be formed a position closer to the axis O than the position of ⅔ of the radial dimension. By forming the fitting surface 37 at the position closer to the axis O than the position of ⅔ of the radial dimension, it is possible to enhance a stress reduction effect.

Moreover, the step section 36 may be formed so as to be larger than 0.1 times the diameter dimension R between the rotation center axis of the impeller body 31 and the outer peripheral end of the impeller body 31 from the rotation center axis (axis O) of the impeller body 31 and such that the center of the reinforcing ring 41 in the radial direction is located at a position smaller than the diameter dimension R. That is, in a case where a distance between the center of the reinforcing ring 41 in the radial direction and the axis O is defined as h, the reinforcing ring 41 may be provided so as to satisfy 0.1R<h<1.0R.

Second Embodiment

Next, a second embodiment of the invention will be described with reference to FIG. 4.

The same constituent elements as those of the first embodiment will be designated by the same reference signs, and the detailed description thereof will be omitted.

The turbocharger 50 of the present embodiment is different from the first embodiment in the shape of a compressor impeller 51.

The compressor impeller 51 is provided with a boss part 53 that protrudes from a back surface of an impeller body 52 to one side in the direction of the axis O.

The impeller body 52 forms substantially the same shape substantially as the impeller body 31 of the first embodiment, and is made of the above-described resin. In the present embodiment, a back surface 54 of the impeller body 52 extends in the radial direction, and is curved smoothly toward one side in the direction of the axis O as it becomes closer to the radial inner side.

The boss part 53 is formed integrally with the impeller body 52 at a position on the radial inner side in the impeller body 52, and forms an annular shape about the axis O. A boss hole section 53 a that is continuous with the boss hole section 31 b is formed at the boss part 53. The rotating shaft 2 is fitted to the boss hole section 53 a.

The boss part 53 has a fitting surface 57 that faces the radial outer side. The fitting surface 57 is smoothly continuous with the curved back surface 54 of the impeller body 52. Accordingly, the fitting surface 57 is formed in a rounded shape that is smoothly curved toward one side in the direction of the axis O so as to run in the direction of the axis O as it becomes closer to the radial inner side.

When an inner peripheral surface 65 of the reinforcing ring 41 contacts the fitting surface 57 of the boss part 53, a reinforcing ring 61 is fitted to the boss part 53. That is, in the present embodiment, a step section 56 having the fitting surface 57 is formed at the boss part 53, and the reinforcing ring 61 is fitted to the step section 56.

Here, in the reinforcing ring 61 of the present embodiment, the shape of a cross-section including the axis O does not form a rectangular shape, and the shape of this cross-section is such that the inner peripheral surface 65 that faces the radial inner side becomes a curved surface that forms a convex shape toward the axis O. The shape of this curved surface corresponds to the curved shape of the fitting surface 57.

Additionally, an outer peripheral surface 66 that extends substantially parallel to the axis O continuously with the inner peripheral surface 65, which becomes the above curved surface, and faces the radial outer side, and an axial surface 67 that connects the inner peripheral surface 65 and the outer peripheral surface 66 together, is orthogonal to the axis O, and faces one side in the direction of the axis O are formed in the reinforcing ring 61.

According to the turbocharger 50 of the present embodiment described above, the material of the reinforcing ring 61 and the material of the impeller body become substantially the same. For this reason, a difference between the coefficients of linear expansion of the impeller body 52 and the reinforcing ring 61 becomes small. As a result, the constraint force of the impeller body 52 can be inhibited from decreasing due to an increase in the diameter of the reinforcing ring 61 caused by thermal expansion. Additionally, since the density of the resin is low compared to the metal or the like, the constraint force of the impeller body 52 can be inhibited from decreasing by the diameter of the reinforcing ring 61 being increased due to a centrifugal force.

Moreover, since the reinforcing ring 61 includes the carbon fibers as the reinforcing resin, the constraint force of the impeller body 52 can be inhibited from decreasing by a diameter increase caused by the centrifugal force of the reinforcing ring 61 itself, and even if the resin is used for the impeller body 52, it is possible to sufficiently suppress deformation.

Analysis results obtained by plotting the ratios of stresses generated in the impeller body 52 in a case where the reinforcing ring 61 is provided at the boss part 53 of the impeller body 52 for each relative position coordinate of the impeller body 52 in the direction of the axis O are illustrated in FIG. 5. Additionally, the formation range of the boss part 53 is within a range of 0 to 1.0.

In this analysis, the thickness dimension of the reinforcing ring 61 in the direction of the axis O is 0.15 times the thickness of the impeller body 31 in the direction of the axis O and the width dimension of the reinforcing ring 61 in the radial direction is 0.05 times the external diameter of the impeller body 31. The other analysis conditions are the same as those illustrated in FIG. 3 in the first embodiment.

According to the analysis results of FIG. 5, since the reinforcing ring 61 is provided at the position (a position where a relative position coordinate larger than about 0.9) of the boss part 53 of the impeller body 52, it can be confirmed that a stress can be markedly reduced at a position where a relative position coordinate in the direction of the axis O becomes larger than about 0.6 compared to a case (dashed line) where the reinforcing ring 61 is not provided. Stresses decrease gradually at position coordinates of about 0.6 to about 0.9, and a stress ratio can be suppressed to about 0.25 at a position of about 0.9, that is, at a portion where the impeller body 52 and the boss part 53 are connected together.

Therefore, by providing the reinforcing ring 61 at the boss part 53 of the impeller body 52, a stress caused by a centrifugal force in the boss part 53 can be reduced, a stress generated in the impeller body 52 can be reduced, and deformation of the entire compressor impeller 51 can be further suppressed.

Third Embodiment

Next, a third embodiment of the invention will be described with reference to FIG. 6.

The same constituent elements as those of the first and second embodiments will be designated by the same reference signs, and the detailed description thereof will be omitted.

In a turbocharger 70 of the present embodiment, the compressor impeller 24 (or the compressor impeller 51 of the second embodiment) of the first embodiment further includes a second reinforcing ring 71.

An annular groove part 75 of the rotating shaft 2 that is recessed to the radial outer side and runs in the circumferential direction is formed in an inner peripheral surface of the boss hole section 31 b.

As the annular groove part 75, an inside groove part 75 a that opens to the inner peripheral surface of the boss hole section 31 b, extends to the radial outer side, and forms a rectangular shape as the shape of a cross-section including the axis O, and an outside groove part 75 b that communicates with the inside groove part 75 a, extends to the radial outer side, and forms a rectangular shape, which protrudes to both sides of the axis O from the inside groove part 75 a, as the shape of a cross-section including the axis O are formed.

That is, the annular groove part 75 has a T-shaped cross-section.

The second reinforcing ring 71 is disposed inside the annular groove part 75 of the impeller body 31. Namely, the second reinforcing ring 71 has a base part 72 that has a rectangular cross-section corresponding to the inside groove part 75 a and forms an annular shape in the circumferential direction of the impeller body 31, and an engaging part 63 that extends to both sides in the direction of the axis O from the base part 72, on the radial outer side closer to the inside of the impeller body 31 than the base part 72 continuously with the base part 72.

The second reinforcing ring 71 is disposed without a gap inside the annular groove part 75. The base part 72 is exposed to the inner peripheral surface of the boss hole section 31 b and is flush with the inner peripheral surface. In this way, the second reinforcing ring 71 forms an annular shape about the axis O and has a T-shaped cross-section, in a state where the second reinforcing ring is disposed inside the impeller body 31.

The second reinforcing ring 71 is formed of a complex material including a thermosetting resin and reinforcing fibers. Here, as the reinforcing fibers, similar to the reinforcing ring 41, carbon fibers, glass fibers, Whisker, and the like can be used. Additionally, as the thermosetting resin, phenol resins, epoxy resins, melamine resins, silicon resins, and the like can be used.

Here, the second reinforcing ring 71 may be formed of metallic materials, such as aluminum, instead of the complex material.

The second reinforcing ring 71 is provided to be fitted into the impeller body 31, for example by insert molding.

According to the turbocharger 70 of the present embodiment described above, the rigidity of the impeller body 31 can be improved by disposing the second reinforcing ring 71 inside the impeller body 31 made of the resin in the compressor impeller 24. Additionally, since the second reinforcing ring 71 is disposed inside the impeller body 31, slip-out from the impeller body 31 can be suppressed even if a material having a different coefficient of linear expansion from the impeller body 31 is used. Therefore, a centrifugal force that acts on the impeller body 31 can be distributed to the second reinforcing ring 71, a stress generated in the impeller body 31 due to the centrifugal force can be reduced, and it is possible to suppress deformation of the entire compressor impeller 24.

Moreover, since the second reinforcing ring 71 has the base part 72, and an engaging part 73 continuous with the base part 72, when a tensile force acts on the impeller body 31 to the radial outer side due to the centrifugal force in a case where the impeller body 31 has rotated, the engaging part 73 is caught inside the impeller body 31, so that the centrifugal force that acts on the impeller body 31 can be firmly distributed to the second reinforcing ring 71. Therefore, it is possible to further reduce the stress generated in the impeller body 31, and deformation of the impeller body 31 can be suppressed.

Additionally, since the second reinforcing ring 71 is formed of the complex material including the thermosetting resin and the reinforcing fibers, and thereby the coefficient of linear expansion of the complex material is small compared to metals, slackening of the second reinforcing ring 71 with respect to the impeller body 31 due to thermal expansion does not easily occur. Therefore, a centrifugal force that acts on the impeller body 31 can be effectively distributed to the second reinforcing ring 71, and it is possible to further reduce a stress generated in the impeller body 31.

Additionally, in a case where the second reinforcing ring 71 is formed of a metallic material, the rigidity of the second reinforcing ring 71 itself becomes high. Therefore, deformation does not easily occur when a centrifugal force has acts, and slackening of the second reinforcing ring 71 with respect to the impeller body 31 does not easily occur. Therefore, a centrifugal force that acts on the impeller body 31 can be effectively distributed to the second reinforcing ring 71, and a stress generated in the impeller body 31 can be further reduced.

Here, as illustrated in FIG. 7, the second reinforcing ring 71A may have a christmas tree-shaped cross-section. By including such a cross-sectional shape, the second reinforcing ring 71A has a curved engaging surface 80 that is an outer surface that is curved so as to protrude toward the impeller body 31. By providing the curved engaging surface 80 in this way, when a tensile force to the radial outer side caused by a centrifugal force has acted on the impeller body 31, the concentration of a stress generated in the impeller body 31 can be suppressed at a position where the second reinforcing ring 71A and the impeller body 31 contact each other. For this reason, further suppression of deformation or damage of the impeller body 31 is possible by the curved engaging surface 80.

In addition, in the above-described case, the shapes of the second reinforcing rings 71 and 71A are not limited.

Additionally, the second reinforcing rings 71 and 71A may be disposed at a position in the direction of the axis O where a stress generated in the impeller body 31 reaches a maximum.

Additionally, the second reinforcing rings 71 and 71A are not exposed to the inner peripheral surface of the boss hole section 31 b, and may be completely embedded inside the impeller body 31.

Although the embodiments of the invention have been described above in detail, some design changes can also be made without departing from the technical idea of the invention.

For example, the sectional shapes of the reinforcing rings 41 and 61 is not limited are not limited to the cases of the above-described embodiments.

That is, a circular cross-sectional shape and the like may be adopted.

Additionally, the thickness dimension (the thickness dimension in the circumferential direction) of the compressor blades 25 may be the same as the width dimension a (refer to FIG. 2) of the reinforcing ring 41 (61) in the radial direction.

Moreover, the thickness dimension b (refer to FIG. 2) of the reinforcing ring 41 (61) in the direction of the axis O may be larger than the width dimension a in the radial direction.

By doing in this way, the stress of the impeller body 31 (52) generated by a centrifugal force can be more effectively reduced, and deformation of the entire compressor impeller 24 (51) can be suppressed.

Additionally, the reinforcing fibers may be disposed so as to extend in the circumferential direction of the rotating shaft 2.

If a centrifugal force acts on the reinforcing ring 41 (61), a tensile force acts in the circumferential direction such that the diameter of the reinforcing ring increases. For this reason, if the reinforcing fibers extends in the circumferential direction that is a direction in which this tensile force acts, deformation of the reinforcing ring 41 (61) by such a tensile force itself can be suppressed. Therefore, the constraint force of the impeller body 31 (52) can be inhibited from decreasing, and a centrifugal force that acts on the impeller body 31 (52) can be distributed to the reinforcing ring 41 (61).

Therefore, the stress of the impeller body 31 (52) can be reduced, and deformation of the entire compressor impeller 24 (51) can be suppressed.

Additionally, the reinforcing ring 41 (61) may be formed of only the carbon fibers excluding the resin.

Additionally, the compressor blades 25 and the impeller body 31 (52) may include the same reinforcing fibers as the reinforcing ring 41 (61) in addition to the resin.

Additionally, in the above-described embodiments, as the rotary machine, the turbocharger has been described as an example. However, the invention may be used for other centrifugal compressors and the like.

INDUSTRIAL APPLICABILITY

According to the above-described impeller and rotary machine, the reinforcing ring is provided. Thus, even if resin materials are used, it is possible to guarantee reliability.

REFERENCE SIGNS LIST

1: TURBOCHARGER

2: ROTATING SHAFT

3: TURBINE

4: COMPRESSOR

5: HOUSING COUPLING PART

6: BEARING

11: TURBINE HOUSING

12: SCROLL PASSAGE

13: DISCHARGE PORT

14: TURBINE IMPELLER

15: TURBINE BLADE

21: COMPRESSOR HOUSING

22: COMPRESSOR PASSAGE

23: SUCTION PORT

24: COMPRESSOR IMPELLER

25: COMPRESSOR BLADE

31: IMPELLER BODY

31 a: HUB SURFACE

31 b: BOSS HOLE SECTION

32: BACK SURFACE

32A: FIRST BACK SURFACE

32B: SECOND BACK SURFACE

36: STEP SECTION

37: FITTING SURFACE

41: REINFORCING RING

50: TURBOCHARGER (ROTARY MACHINE)

51: COMPRESSOR IMPELLER

52: IMPELLER BODY

53: BOSS PART

53 a: BOSS HOLE SECTION

54: BACK SURFACE

56: STEP SECTION

57: FITTING SURFACE

61: REINFORCING RING

65: INNER PERIPHERAL SURFACE

66: OUTER PERIPHERAL SURFACE

67: AXIAL SURFACE

70: TURBOCHARGER

71, 71A: SECOND REINFORCING RING

72: BASE PART

73: ENGAGING PART

75: ANNULAR GROOVE PART

75 a: INSIDE GROOVE PART

75 b: OUTSIDE GROOVE PART

80: CURVED ENGAGING SURFACE

G: EXHAUST GAS

AR: AIR

O: AXIS

FC: FLOW PASSAGE 

1. An impeller comprising: an impeller body that is formed of a resin, forms a disk-like shape, and rotates about a rotation center axis together with a rotating shaft; a plurality of blades provided on a front surface side of the impeller body; and a reinforcing ring that is formed on a back surface of the impeller body, is fitted to a step section, having a surface facing an outer peripheral side, from the outer peripheral side, is formed of a resin and reinforcing fibers, and forms an annular shape in a circumferential direction of the impeller body.
 2. The impeller according to claim 1, wherein the step section is formed at a position of ⅔ of a diameter dimension between the rotation center axis and an outer peripheral end of the impeller body from the rotation center axis.
 3. The impeller according to claim 1, wherein the step section is formed such that the center of the reinforcing ring in a radial direction is located at a position that is larger than 0.1 times a diameter dimension between the rotation center axis and an outer peripheral end of the impeller body from the rotation center axis and is smaller than the diameter dimension.
 4. The impeller according to claim 1, wherein the impeller body is provided with a boss part that protrudes from the back surface and has the rotating shaft fitted thereto, and wherein the step section is formed at the boss part.
 5. The impeller according to claim 1, wherein a width dimension of the reinforcing ring in a radial direction and a blade thickness dimension of the blades in the circumferential direction are the same, and a thickness dimension of the reinforcing ring in a direction of the rotation center axis is larger than the width dimension of the reinforcing ring in the radial direction.
 6. The impeller according to claim 1, wherein the reinforcing ring is disposed such that the reinforcing fibers extend in the circumferential direction of the impeller body.
 7. An impeller comprising: an impeller body that is formed of a resin, forms a disk-like shape, and rotates about a rotation center axis together with a rotating shaft; a plurality of blades provided on a front surface side of the impeller body; and a reinforcing ring that is formed on a back surface of the impeller body, is provided at a step section, having a surface facing an outer peripheral side, from the outer peripheral side, is formed of only reinforcing fibers, and forms an annular shape in a circumferential direction of the impeller body.
 8. The impeller according to claim 1, further comprising: a second reinforcing ring that is disposed in the circumferential direction of the impeller body inside the impeller body and forms an annular shape.
 9. A rotary machine comprising: the impeller according to claim 1; and a rotating shaft that is attached to the impeller and rotates together with the impeller.
 10. The impeller according to claim 2, wherein a width dimension of the reinforcing ring in a radial direction and a blade thickness dimension of the blades in the circumferential direction are the same, and a thickness dimension of the reinforcing ring in a direction of the rotation center axis is larger than the width dimension of the reinforcing ring in the radial direction.
 11. The impeller according to claim 3, wherein a width dimension of the reinforcing ring in a radial direction and a blade thickness dimension of the blades in the circumferential direction are the same, and a thickness dimension of the reinforcing ring in a direction of the rotation center axis is larger than the width dimension of the reinforcing ring in the radial direction.
 12. The impeller according to claim 4, wherein a width dimension of the reinforcing ring in a radial direction and a blade thickness dimension of the blades in the circumferential direction are the same, and a thickness dimension of the reinforcing ring in a direction of the rotation center axis is larger than the width dimension of the reinforcing ring in the radial direction.
 13. The impeller according to claim 2, wherein the reinforcing ring is disposed such that the reinforcing fibers extend in the circumferential direction of the impeller body.
 14. The impeller according to claim 3, wherein the reinforcing ring is disposed such that the reinforcing fibers extend in the circumferential direction of the impeller body.
 15. The impeller according to claim 4, wherein the reinforcing ring is disposed such that the reinforcing fibers extend in the circumferential direction of the impeller body.
 16. The impeller according to claim 5, wherein the reinforcing ring is disposed such that the reinforcing fibers extend in the circumferential direction of the impeller body.
 17. The impeller according to claim 2, further comprising: a second reinforcing ring that is disposed in the circumferential direction of the impeller body inside the impeller body and forms an annular shape.
 18. The impeller according to claim 3, further comprising: a second reinforcing ring that is disposed in the circumferential direction of the impeller body inside the impeller body and forms an annular shape.
 19. The impeller according to claim 4, further comprising: a second reinforcing ring that is disposed in the circumferential direction of the impeller body inside the impeller body and forms an annular shape.
 20. The impeller according to claim 5, further comprising: a second reinforcing ring that is disposed in the circumferential direction of the impeller body inside the impeller body and forms an annular shape. 